Direct imaging discovery of 12-14 Jupiter mass object orbiting a young binary system of very low-mass stars

Fig. 1. 2MASS0103(AB)b in November 2012, with NACO in L' band. The green arrow shows the position of the companion in 2002. The light-blue circle identifies the expected position of the companion if it had been a background source.

Context. Though only a handful of extrasolar planets have been discovered via direct imaging, each of these discoveries had tremendous impact on our understanding of planetary formation, stellar formation and cool atmosphere physics. Aims. Since many of these newly imaged giant planets orbit massive A or even B stars we investigated whether giant planets could be found orbiting low-mass stars at large separations. Methods.

We have been conducting an adaptive optic imaging survey to search for planetary-mass companions of young M dwarfs of the solar neigbourhood, to probe different initial conditions of planetary formation. Results. We report here the direct imaging discovery of 2MASS J01033563-5515561(AB)b, a 12-14 MJup companion at a projected separation of 84 AU from a pair of young late M stars, with which it shares proper motion. We also detected a Keplerian-compatible orbital motion. Conclusions. This young L-type object at planet/brown dwarf mass boundary is the first ever imaged around a binary system at a separation compatible with formation in a disc.